Kinder, Gentler Demolition: A Bright Idea from Japan

Demolition of the Boardwalk hotel in Las Vegas in 2006. Photo via Vegas.com

The implosion of a Las Vegas hotel is, like everything else in Sin City, a spectacle, with fireworks, multi-story countdown lights, crowds gathered to watch, and a big, cool crash at the end. Taking a large building down floor by floor is not as good as a spectator sport, but, a Japanese firm has shown, it's a lot better for the environment.So-called "upside-down demolition," featured in the 2008 installment of The New York Times Magazine's "Year in Ideas" issue, creates less air pollution than demolition by explosives and makes it easier to recycle construction materials--up to 92.2 percent of an office building's interior. The process, pioneered by the Japanese construction firm Kajima Corporation,

is a modification of a technique the firm previously used to erect a high-rise building. Using computer-controlled hydraulic jacks in place of supports, they’d build the top floor at ground level, then lever it up, build the next, lever that up and so on until the project was finished.

This approach was easily adapted for use as a demolition method. The support pillars of a building’s lowermost floor are replaced with a series of jacks until the entire weight of the building rests on them. Next, workers come in, smash the interior, remove the walls and cart the rubble away for recycling. Finally, the building is lowered to the ground, one story shorter than before. And then the process is repeated.